Detection of Spiral photons in Quantum Optics

TL;DR

This paper proposes a new photon detector sensitive to electromagnetic field gradients, enabling quantum-level analysis of the spatial and angular momentum properties of spiral photons in Laguerre-Gauss beams.

Contribution

It introduces a novel detection method using atomic magnetic dipole or electric quadrupole transitions to characterize quantum properties of spatially-dependent optical fields.

Findings

LG beams are not truly hollow due to magnetic and electric field gradients on the axis.

The proposed detector can analyze the quantum spatial structure of singular light beams.

This method advances understanding of the angular momentum in complex optical fields.

Abstract

We show that a new type of photon detector, sensitive to the gradients of electromagnetic fields, should be a useful tool to characterize the quantum properties of spatially-dependent optical fields. As a simple detector of such a kind, we propose using magnetic dipole or electric quadrupole transitions in atoms or molecules and apply it to the detection of spiral photons in Laguerre-Gauss (LG) beams. We show that LG beams are not true hollow beams, due to the presence of magnetic fields and gradients of electric fields on beam axis. This approach paves the way to an analysis at the quantum level of the spatial structure and angular momentum properties of singular light beams.